1. Field of the Invention
This invention relates to components for an insulating glazing unit and to methods of making same and, in particular, to a spacer and spacer frame for an insulating glazing unit and methods of making same.
2. Discussion of the Technical Problems
It is well recognized that insulating glazing units reduce heat transfer between the outside and inside of a home or other structures. A measure of insulating value generally used is the "U-value". The U-value is the measure of heat in British Thermal Unit (BTU) passing through the unit per hour (Hr) per square foot (sq.ft.) per degree Fahrenheit (.degree.F.). As can be appreciated the lower the U-value the better the thermal insulating value of the unit, i.e. higher resistance to heat flow resulting in less heat conducted through the unit. Another measure of insulating value is the "R-value" which is the inverse of the U-value. Still another measure is the resistance (RES) to heat flow which is stated in Hr-.degree.F. per BTU per inch of perimeter of the unit. In the past the insulating property, e.g. U-value given for an insulating unit was the U-value measured at the center of the unit. Recently it has been recognized that the U-value of the edge of the unit must be considered separately to determine the overall thermal performance of the unit. For example, units that have a low center U-value and high edge U-value during the winter season exhibit no moisture condensation at the center of the unit, but may have condensation or even a thin line of ice at the edge of the unit near the frame. The condensation or ice at the edge of the unit indicates that there is heat loss through the edge of the unit and/or frame i.e. the edge has a high U-value.
Through the years, the design of and construction materials used to fabricate insulating glazing units, and the frames have improved to provide framed units having low U-values. Several types of insulating glazing units presently available, and or center and edge U-values of selected ones, are taught in U.S. patent application Ser. No. 07/468,039 assigned to PPG Industries, Inc. filed on Jan. 22, 1990, in the names of P. J. Kovacik et al. and entitled METHOD OF AND APPARATUS FOR JOINING EDGES OF GLASS SHEETS, ONE OF WHICH HAS AN ELECTROCONDUCTIVE COATING AND THE ARTICLE MADE THEREBY, and U.S. Pat. Nos. 3,919,023; 4,431,691; 4,807,419; 4,831,799 and 4,873,803. The teachings of the patent application and patents are hereby incorporated by reference.
U.S. patent application Ser. No. 07/578,697 filed even date in the names of Stephen C. Misera and William R. Siskos and entitled INSULATING GLAZING UNIT HAVING A LOW THERMAL CONDUCTING EDGE AND METHOD OF MAKING SAME teaches the design of and methods of making an insulating unit having a low thermal conducting edge. In Section 2 Discussion of Available Insulating Units, the drawbacks and/or limitations of the insulating units of the above identified patent application and patents are discussed. The teachings of U.S. patent application Ser. No. 07/578,697 are hereby incorporated by reference.
As can be appreciated, it would be advantageous to provide a spacer and spacer frame, and method of making same that can be used to fabricate insulating units taught in U.S. patent application Ser. No. 07/578,697 as well as other types of insulating units.